A compound contains only carbon, hydrogen, nitrogen, and oxygen. Combustion of a 2.18 g sample burns in excess oxygen yields 3.94 g of CO2 and 1.89 g of H2O. A separate experiment shows that a 1.23 g sample contains 0.235 g of N. Calculate the moles of C in the sample.
1. Calculate the moles of N for a 2.18 g sample (the sample size for the other analyses).
2. Calculate the moles of O in the sample.

The answers are

C = 0.0895 moles

1. 0.02975 moles of N

2. 0.0299 moles O

Explanation:

Mass of sample = 2.18 g

Combustion yields 3.94 g of CO₂ and 1.89 g of H₂O

1.23 g of sample contains 0.235 g of N

3.94 g of CO₂ which contains one mole of C and two moles of O

Molar mass of CO₂ = 44 mass fraction of C = 12/44 = 0.273, Therefore mass of  carbon in 2.18 g = 0.273×3.94 = 1.075 g

number of moles of C in sample = mass/(molar mass) = 1.075 g/(12.01 g/mol) = 0.0895 moles of C

(1) Mass of nitrogen, in 1.23 g of sample = 0.235

therefore mass in 2.18 g =0.235×2.18/1.23 = 0.4165 g

= 0.02975 moles of N

(2) To find the number of moles of oxygen in the sample we note that total mass of sample  = 2.18 g containing only nitrogen, hydrogen, oxygen and carbon

Mass of hydrogen can be fround from 2/18×1.89 = 0.21 g

Mass of oxygen therefore = 2.18 -(0.21+0.4165+1.075) = 0.4785  

number of moles = 0.475/16 = 0.0299 moles

when [oh-] is 10-5  m, and [h3o+] is 10-9  m, the poh is 5 and ph is 9. again in both cases the sum of ph and poh is 14. however, the hydrogen ion concentration is not always going to be equal to exactly 1 x 10 raised to a negative number. for example, we skipped over the value of 2.0 x 10-7.

answer: any goods being imported from another country may be subject to issued by the federal government are tariffs

explanation:  

tariffs are a tax on anything that are imported from abroad. government use them to protect and boost their local industries and the thought is that they encourage consumers to buy local instead of importing and they will hope will protect jobs and economy in the country that implements them